Automatic trip device for plug-in circuit breaker



Nov. 12, 1963 w. H. EDMUNDS 3,110,778

AUTOMATIC TRIP DEVICE FOR PLUG-IN CIRCUIT BREAKER Filed Jan. 7, 1960 5 Sheets-Sheet 1 INV TOR. W/ 4mm flmeazp a/vwms dire ewe, naae, @595 @FFE/V Nov. 12, 1963 w. H. EDMUNDS AUTOMATIC TRIP DEVICE FOR PLUG-IN cmcun BREAKER Fil ed Jan; 7, 19 0 3 Sheets-Sheet 2 arma/vzrr Nov. 12, 1963 v w. H. EDMUNDS 3,110,773

AUTOMATIC TRIP DEVICE FOR PLUG-IN CIRCUIT BREAKER Filed Jan. 7, 1960 s Sheets-Sheet a 7IIIIIIIIIIIIIIII/II/A III dire mg, fheie, 654's Ema-M A 7' WZWE' Z1 INVENZ'OR. w/zz MMMmmmM/Nw United States Patent 3,110,778 AUTGMA'IEC TRIP DEVICE FOR PLUG-IN CRCUIT BREAKER William Harold lildmunds, Haven-town, Pa, assignor to I-T-E Circuit Breaker Company, Philadelphia, Pin, a

corporation of Pennsylvania Filed Jan. 7, 1960, Ser. No. 1,014 2 Claims. (Cl. 2t?5) My invention relates to circuit breakers of the plug-in type wherein the circuit breaker will be automatically tripped before it can be unplugged from its switchboard mounting.

A very common application of circuit breakers finds the circuit breakers mounted to a switchboard panel. The most desirable type of switchboard mounting is a plug-in type of arrangement wherein the panelboard provides a first pair of disconnects, while the circuit breaker provides a second pair of cooperating disconnects which can be easily plugged into and removed from the first disconnects on the panelboard.

For illustrative purposes, these disconnects may be of the tulip-clip type wherein a plurality of contact fingers are provided for each of the disconnects with the fingers being spring biased for high pressure contact engagement.

In the event that such a circuit breaker is withdrawn from the panel while the circuit breakers are closed, serious damage can result in the form of arcing at the disconnect contacts. At the present time, conspicuous labels are usually provided to inform the operator that the circuit breaker must be in its off position before attempting to unplug the circuit breaker. However, it is possible that these labels can be lost or disregarded by operating personnel, whereby the above noted damage can occur. 1

The principle of the present invention is to provide an automatic trip device which is not under the control of operating personnel for causing tripping of the circuit breaker before the circuit breaker disconnect contacts are removed from the panelboard disconnect contacts.

In a preferred embodiment of the invention, the automatic trip device is directly operable responsive to the opening of the switchboard housing to gain access to the circuit breaker mounting screws to cause operation of the circuit breaker automatic trip mechanism whereby the contacts of the circuit breaker are automatically opened, notwithstanding any action by the operator.

In a second embodiment of the invention, the automatic trip can be connected between the switchboard mounting member itself and the automatic trip housing of the circuit breaker whereby, once the mounting screws are removed, and the operator begins to bring the circuit breaker disconnect contacts from the panelboard disconnect contacts, the automatic trip mechanism will be operated.

In either case, it is possible to later defeat this mechanism so that tests may be performed, for example, with the switchboard enclosure door in an open position. I

In addition to causing positive operation of the circuit breaker contacts during attempted removal of the circuit breakers, the novel automatic trip device may be further operable to normally prevent the closing of the circuit breaker contacts so that the circuit breaker contacts may not be in the on position when the circuit breaker is connected to the panelboard, and it is only after the connection is made and the door is closed in the appropriate manner that the automatic trip device is defeated, and the circuit breaker can be closed. This feature is not available when the interlock is not taken to the front door.

Accordingly, the primary object of my invention is to provide a novel automatic trip device for plug-in circuit breakers which prevents the removal of circuit breakers from their support while the circuit breaker contacts are closed.

Another object of this invention is to prevent the removal or connection of {plug-in circuit breakers when their contacts are closed.

A' still further object of this invention is to provide a novel interlock mechanism for plug-in circuit breakers which prevent their removal from a switchboard with the circuit breaker contacts in the engaged position.

A still further object of this invention is to provide an interlock between the circuit breaker trip unit and the front door or covering member of the switchboard whereby the circuit breaker contacts are opened responsive to opening or removal of the front door.

A still further object of this invention is to provide an interlock between the trip unit of a circuit breaker and a panel to which the circuit breaker is mountedwhereby the circuit breaker will be operated to its off position responsive to attempts to remove the circuit breaker from the panel while the circuit breaker contacts are in their on position.

These and other objects of this invention will become apparent from the following description when taken in connection with the drawings in which:

FIGURE 1 shows a side cross-sectional view of a typical circuit breaker which may be modified in accordance with the present invention.

FIGURE 2 shows a top view of the circuit breaker of FIGURE 1 with its cover removed.

FIGURE 3 shows a side cross-sectional view of the trip unit of the circuit breaker of FIGURES 1 and 3, and particularly illustrates the manner in which the novel automatic trip device cooperates with the front sheet or front door of the switchboard carrying the circuit breaker.

FIGURE 4 is a top view of a portion of the trip unit of FIGURE 3 with the circuit breaker cover and trip unit housing top removed.

FIGURE 5 shows the trip unit of the circuit breaker of FIGURE 1 as modified in accordance with a second embodiment of the present invention wherein the trip unit is interlocked with the base which receives the plug-in circuit breaker.

Referring now to FIGURES 1 and 2, I have shown a typical circuit breaker of the plug-in type which includes a molded housing 1% and an operating mechanism generally seen as operating mechanism 12. Operating mechanism 12 may be operated manually under the influence of operating handle 14, or automatically under the influence of trip unit 16. The circuit breaker of FIGURES 1 and 2 is a multiphase unit where each phase includes a movable contact, such as movable contact 18 of FIG- URES 1 and 2 which moves under the influence of operating mechanism 12 with respect to a stationary contact 24} within an arc chute 22 in the usual manner.

When the contacts, such as contacts 18 and 20, are in their engaged position, they may be automatically moved to a disengaged position under the influence of trip unit 16, as will be discussed morefully hereinafter, and responsive to the unlatching :of latch member 24 which is connected to operating mechanism 12.

The circuit breaker of FIGURES 1 and 2 is of the plugin type by virtue of plug-in terminals or disconnects, such as tulip-clip type terminals 2 6 and 28 of the central phase of FIGURE 1, and similar terminals (not shown) for each of the other phases where the terminals are connected in series with the current path through the circuit breaker.

The top view of FIGURE 2 shows two terminal positions Sit-32, 3436 (which correspond to terminals 26 and 28 of FIGURE 1) and terminals 38-48 for each of the three phases respectively. The tulip-clip type disconnects corresponding to terminals 39 through do cooperate with cooperating disconnects, such as conductive members 42 and 44 which are carried by a panelboard base schematically shown in FIGURE 1 es panelboard base 46, and specifically cooperate with tulip-clip contacts or disconnects 26 and 28 respectively. In a like manner, each of the other disconnects for the upper and lower phases of FIGURE 2 will be provided with similar cooperating protruding disconnects carried by panelboand 46.

.In order to firmly secure the circuit breaker to the panelboard, mounting bolts are provided which pass through openings 48, 50, 52 and 54 in the circuit breaker base (FIGURE 2) and into a bolt receiving means (not shown) in the panelboard 46. After the unit is mounted, as described above, it is normally enclosed within a switchboard by means of a front door 56 or a front sheet means which has an opening to receive the operating handle 14 in the usual manner.

The trip unit 16, as is best seen in FIGURES 3 and 4, is operable to control the movement of latch member 24 so that, upon predetermined-current conditions, the circuit breaker may be opened. Thus, the trip unit 16 is provided with a heater 58 which is connected in the current carrying circuit of the circuit breaker, and is positioned adjacent a bimetal element 60.

Bimetal element St) is operatively connected (in a manner not shown) to the pivotally mounted tripper bar 62 which carries a cooperating latch '64 which cooperates with latch member 24. Therefore, operation of the bi- 'metal element 6i for any of the circuit breaker phases will cause a rotation of tripper bar 62, and thus will unlatch latch member 24- to permit an automatic tripping of all of the circuit breaker contacts, such as movable circuit breaker contact 18 of FIGURE 1.

All of the foregoing is old and well known, and is typically illustrated, for example in copending application Serial No. 671,531, now US. Patent No. 3,032,629, filed July 12, 1957, in the name of Walter U. Uecker, entitled Tripping 'Mechanism for a Combined Circuit Breaker and Current Limiting Fuse, and assigned to the assignee of the instant invention.

In accordance with the present invention, the trip unit 16 is provided with an extending support platform 66 which has an aperture therein for receiving at least one rod or plunger 68 in the manner shown in FIGURES 3 and 4. It will be noted that one rod 68 is shown for FIGURE 4.

The plunger then passes through an L-shaped extension 7i) which is rigidly fastened to tripper bar 62, as by screws 72 and 7d of FIGURE 4, and has an aperture '76 therein for receiving rod 68.

The top of trip unit housing 16 is provided with an opening '78 for receiving the tip of rod '68, and a cooperating opening 80 is. provided in the housing It of the circuit breaker which also receives rod 68. Rod 68 is then supported with respect to platform 66 by means of a washer 82 which is rigidly attached to rod 68 and a compression spring 84 which is seated between the top of platform 66 and the bottom of washer 82. Rod 68 carries a second washer 86 in a rigid manner, which is positioned a spaced distance below member 7dwhen menrber 7th is in a position corresponding to circuit breaker contact engagement.

In operation, when an operator wishes to remove the circuit breaker from support panel &6 of FIGURE 1, he must first remove the door or front sheet 56 in order to gain access to the bolts passing through bolt receiving apertures 48 through 54 of FIGURE 2. When member 56 is removed, however, compression spring $4 will move rod 63 upwardly whereby the top of washer do will pick up member 7% and rotate tripper bar 62 in a counterclockwise direction. The upward motion of rod as iwill be arrested when its extending end 83 engages the bottom of panel 66. This will remove latch member 64 from latch member 24 whereby the circuit breaker movable oontacts will move to a disengaged position under the influence of operating mechanism 12. 7

Accordingly, the circuit breaker will be opened without any intentional operation on the part of the operator so that the cooperating disconnects, such as disconnects 2 6-23 of the circuit breaker and disconnects 42-44 of panel 46 may be safely removed Without the danger of having a voltage across these disconnects at the time of removal.

in a like manner, when the circuit breaker is to be connected to the panelboard, it will be impossible to have thecircuit breaker contacts in a closed position, since the automatic trip rod 63 holds tripper bar 62 in the counterclockwise position so that latch member 294 cannot be set to permit closing of the circuit breaker contacts. Thus, the circuit breaker must be connected with circuit breaker contacts in their off position, and can only be closed after the front door or sheet 5-6 is closed.

In order to test the circuit breaker when it is disconnected from the switchboard, it is possible to manually depress rod on and perform any required test procedure in which the contacts must be closed;

A second embodiment of the present invention is shown in FiGURE 5 wherein components similar to those described in FlGUR-ES 3 and 4 are given like identifying numerals. in FIGURE 5, the interlock between trip unit 16* and the switchboard or the mounting means for the circuit breaker is achieved by rod 94} which extends through an opening 92 in the bottom of tripunit 16 and a cooperating opening 93 in circuit breaker base to abut against a mounting body or panel 94 which carries the circuit breaker.

In the embodiment of FIGURE 5, rod carries a washer 96 which serves to mount compression spring 98 bet-ween rod as and support panel 66, while an upper washer ltlt) rigidly secured to rod 94) serves to limit the downward motion of rod 9% by engaging panel 66.

A link 192, which is pivotally mounted at stationary pivot 104, has its left-hand end bearing upon an extension 166 of tripper bar 62, and receives the upper end of rod 9b in a clearance opening 108. The right-hand end of linkage 192 is pivotally mounted to rod 90 by pin 110.

Accordingly, when an operator attempts to remove the circuit breaker from its plug-in connection with respect to disconnects carried by panel 94, as the disconnection is initiated, rod 90 will move downwardly under the infiuence of spring 98. This will cause link 102. to rotate in a clockwise direction to cause tripper bar 62 to rotate in a counterclockwise direction, and thus trip the circuit breaker in the same manner as described above.

It will be noted that the embodiment of FIGURE 5 will also prevent closure of the contacts of the circuit breaker in the absence of an intentional defeat of rod 90. Although I have described preferred embodiments of my novel invention, many variations and modifications will now be obvious to those skilled in the art, and I prefer therefore to be limited not by the specific disclosure herein but only by the appended claims.

I claim:

1. :In combination; a circuit breaker and a means for mounting said circuit breaker; said circuit breaker having a pair of cooperable contacts movable between an engaged and disengaged position, a trip mechanism operatively connected to at least one of said pair of cooperable contacts, a housing wherein said contacts and said trip mechanism are disposed and an operating handle extending externally of said housing for operating said contacts'between said positions; said trip mechanism being operable to move said pair of cooperable contacts from said engaged position to said disengaged position; said circuit breaker having a first and second disconnect contact electrically connected in series with said pair of cooperable contacts; said means for mounting said circuit breaker having a first and second disconnect contact adapted to electrically receive said first and second disconnect contact of said circuit breaker; an automatic trip means disposed within said housing and including a portion biased to project external to said housing; said automatic trip means being connected to said trip mechanism of said circuit breaker; said projecting portion engaging said means for mounting said circuit breaker at a point external to said housing; the disengagement of said automatic trip means and said means for mounting said circuit breaker operating said trip mechanism responsive to attempts to remove said circuit breaker from said mounting means, whereby said circuit breaker cooperating contacts must be in said disengaged position when said circuit breaker disconnects are removed from said mounting means disconnects; said trip mechanism including latch means for latching said cooperating contacts in said engaged position; said automatic trip means comprising a spring biased rod operatively connectible to said latch means and biased to defeat said latch means; a first end of said rod being'adapted to project through said housing, a second end of said rod positioned adjacent said latch mechanism; a bar having a first end pivotally connected to said rod near the second end of said rod; said bar being pivotally connected to said housing at a point intermediate its ends; the second end of said bar being adapted to abut said iatch means under control of said spring biased nod to release said latch mechanism.

2. In combination; a circuit breaker and a means for mounting said circuit breaker; said circuit breaker having a pair of cooperable contacts movable between an engaged and disengaged position, a trip mechanism operatively connected to at least one of said pair of cooperable contacts, a housing wherein said contacts and said trip mechanism are disposed and an operating handle extending externally of said housing for operating said contacts between said positions; said trip mechanism being operable to move said pair of cooperable contacts from said engaged position to said disengaged position; said circuit breaker having a first and second disconnect contact electrically connected in series with said pair of co- I operable contacts; said means for mounting said circuit breaker having a first and second disconnect contact adapted to electrically receive said first and second disconnect contact of said circuit breaker; an automatic trip means disposed within said housing and including a portion biased to project external to said housing; said automatic trip means being connected to said trip mechanism of said circuit breaker; said projecting portion engaging said means for mounting said circuit breaker at a point external to said housing; the disengagement of said automatic trip means and said means for mounting said circuit reaker operating said trip mechanism responsive to attempts to remove said circuit breaker from said mounting means, whereby said circuit breaker cooperating contacts must be in said disengaged position when said circuit breaker disconnects are removed from said mounting means discornects; said trip mechanism including latch means for latching said cooperating contacts in said engaged position; said automatic trip means comprising a spring biased rod operatively connectable to said latch means and biased to defeat said latch means; a first end of said rod being adapted to project through said housing, a second end of said rod positioned adjacent said latch mechanism; a bar having a first end pivotally connected to said rod near the second end of said rod; said bar being pivotally connected to said housing at a point intermediate its ends; the second end of said bar being adapted to abut said latch means under control of said spring biased rod to release said latch mechanism; the spring biasing being provided by a helical spring means having said rod threaded therethrough and being compressed between said housing and a shoulder provided near the first end of said rod.

References Cited in the file of this patent UNITED STATES PATENTS 1,515,759 Scott Nov. 18, 1924 2,888,535 Edmunds May 26, 1959 3,009,036 Dortman et al Nov. 14, 1961 FOREIGN PATENTS 556,294 Canada Apr. 22, 1958 1,183,823 France Feb. 2, 1959 

1. IN COMBINATION; A CIRCUIT BREAKER AND A MEANS FOR MOUNTING SAID CIRCUIT BREAKER; SAID CIRCUIT BREAKER HAVING A PAIR OF COOPERABLE CONTACTS MOVABLE BETWEEN AN ENGAGED AND DISENGAGED POSITION, A TRIP MECHANISM OPERATIVELY CONNECTED TO AT LEAST ONE OF SAID PAIR OF COOPERABLE CONTACTS, A HOUSING WHEREIN SAID CONTACTS AND SAID TRIP MECHANISM ARE DISPOSED AND AN OPERATING HANDLE EXTENDING EXTERNALLY OF SAID HOUSING FOR OPERATING SAID CONTACTS BETWEEN SAID POSITIONS; SAID TRIP MECHANISM BEING OPERABLE TO MOVE SAID PAIR OF COOPERABLE CONTACTS FROM SAID ENGAGED POSITION TO SAID DISENGAGED POSITION; SAID CIRCUIT BREAKER HAVING A FIRST AND SECOND DISCONNECT CONTACT ELECTRICALLY CONNECTED IN SERIES WITH SAID PAIR OF COOPERABLE CONTACTS; SAID MEANS FOR MOUNTING SAID CIRCUIT BREAKER HAVING A FIRST AND SECOND DISCONNECT CONTACT ADAPTED TO ELECTRICALLY RECEIVE SAID FIRST AND SECOND DISCONNECT CONTACT OF SAID CIRCUIT BREAKER; AN AUTOMATIC TRIP MEANS DISPOSED WITHIN SAID HOUSING AND INCLUDING A PORTION BIASED TO PROJECT EXTERNAL TO SAID HOUSING; SAID AUTOMATIC TRIP MEANS BEING CONNECTED TO SAID TRIP MECHANISM OF SAID CIRCUIT BREAKER; SAID PROJECTING PORTION ENGAGING SAID MEANS FOR MOUNTING SAID CIRCUIT BREAKER AT A POINT EXTERNAL TO SAID HOUSING; THE DISENGAGEMENT OF SAID AUTOMATIC TRIP MEANS AND SAID MEANS FOR MOUNTING SAID CIRCUIT BREAKER OPERATING SAID TRIP MECHANISM RESPONSIVE TO ATTEMPTS TO REMOVE SAID CIRCUIT BREAKER FROM SAID MOUNTING MEANS, WHEREBY SAID CIRCUIT BREAKER COOPERATING CONTACTS MUST BE IN SAID DISENGAGED POSITION WHEN SAID CIRCUIT BREAKER DISCONNECTS ARE REMOVED FROM SAID MOUNTING MEANS DISCONNECTS; SAID TRIP MECHANISM INCLUDING LATCH MEANS FOR LATCHING SAID COOPERATING CONTACTS IN SAID ENGAGED POSITION; SAID AUTOMATIC TRIP MEANS COMPRISING A SPRING BIASED ROD OPERATIVELY CONNECTIBLE TO SAID LATCH MEANS AND BIASED TO DEFEAT SAID LATCH MEANS; A FIRST END OF SAID ROD BEING ADAPTED TO PROJECT THROUGH SAID HOUSING, A SECOND END OF SAID ROD POSITIONED ADJACENT SAID LATCH MECHANISM; A BAR HAVING A FIRST END PIVOTALLY CONNECTED TO SAID ROD NEAR THE SECOND END OF SAID ROD; SAID BAR BEING PIVOTALLY CONNECTED TO SAID HOUSING AT A POINT INTERMEDIATE ITS ENDS; THE SECOND END OF SAID BAR BEING ADAPTED TO ABUT SAID LATCH MEANS UNDER CONTROL OF SAID SPRING BIASED ROD TO RELEASE SAID LATCH MECHANISM. 